Performing a cost analysis in spine outcomes research: comparing ventral and dorsal approaches for cervical spondylotic myelopathy

Neurosurgery. 2012 Apr;70(4):860-7; discussion 867. doi: 10.1227/NEU.0b013e3182367272.


Background: Medical cost analysis is increasingly important, but the methodology is complex and varied.

Objective: To illustrate how different cost analysis methodologies influence conclusions generated from data from a prospective nonrandomized trial for treatment of cervical spondylotic myelopathy.

Methods: Patients 40 to 85 years of age with degenerative cervical spondylotic myelopathy were enrolled from 7 sites over 2 years (2007-2009). Patients were treated with ventral or dorsal fusion surgery, and outcomes were measured to 1 year postoperatively. A hospital-based cost analysis was performed using Medicare cost-to-charge ratios (CCRs) multiplied by hospital charges from the index hospitalization (CCR method). A society-based cost analysis was performed by estimating costs from the index hospitalization using Medicare coding reimbursement (the Medicare reimbursement method). A separate outpatient cost analysis was performed on a subset of 20 patients.

Results: Of the 85 patients analyzed, 72 had 1-year follow-up. The CCR method showed a difference in upfront direct costs between the dorsal and ventral approaches ($27,942 ± 14,220 vs $21,563 ± 8721; P = .02). Overall upfront direct costs with the Medicare reimbursement method were not different. With the CCR method, the ventral approach dominates an incremental cost-effectiveness ratio analysis. With the Medicare reimbursement method, the incremental cost-effectiveness ratio for ventral surgery is $34,533, the cost of 1 additional quality-adjusted life-year gained by using ventral instead of dorsal surgery. In the subanalysis, outpatient costs were less after ventral surgery than dorsal surgery ($1997 ± 1211 vs $4734 ± $2874; P = .006).

Conclusion: The choice of cost methodology may substantially influence the final results of an economic study.

Publication types

  • Comparative Study
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Cervical Vertebrae
  • Costs and Cost Analysis / methods*
  • Humans
  • Middle Aged
  • Outcome Assessment, Health Care / methods*
  • Quality-Adjusted Life Years
  • Spinal Fusion / economics*
  • Spinal Fusion / methods*
  • Spondylosis / economics*
  • Spondylosis / surgery
  • Treatment Outcome